Provided are methods and apparatuses for densifying a silicon carbide film using remote plasma treatment. Operations of remote plasma deposition and remote plasma treatment of the silicon carbide film alternatingly occur to control film density. A first thickness of silicon carbide film is deposited followed by a remote plasma treatment, and then a second thickness of silicon carbide film is deposited followed by another remote plasma treatment. The remote plasma treatment can flow radicals of source gas in a substantially low energy state, such as radicals of hydrogen in a ground state, towards silicon carbide film deposited on a substrate. The radicals of source gas in the substantially low energy state promote cross-linking and film densification in the silicon carbide film.
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1. A method of densifying a silicon carbide film, the method comprising: providing a substrate in a reaction chamber; depositing a first thickness of a silicon carbide material on the substrate in a first step of a process of depositing a silicon carbide film; exposing the first thickness of the silicon carbide material to remote hydrogen plasma treatment, wherein the first thickness of the silicon carbide material is densified during the process of depositing the silicon carbide film; depositing a second thickness of a silicon carbide material over the first thickness of the silicon carbide material in a second step of the process of depositing the silicon carbide film; and exposing the second thickness of the silicon carbide material to remote hydrogen plasma treatment, wherein the second thickness of the silicon carbide material is densified in the process of depositing the silicon carbide film, wherein each of the first thickness and the second thickness is between about 5 Å and about 30 Å.
A method for making silicon carbide film denser involves alternating deposition of thin layers and remote plasma treatment. A substrate is placed in a reaction chamber. A thin layer (5-30 Angstroms) of silicon carbide is deposited on the substrate. This layer is then treated with remote hydrogen plasma to increase its density. A second thin layer (5-30 Angstroms) of silicon carbide is deposited on top of the first layer, and again treated with remote hydrogen plasma for densification. This process helps create a denser silicon carbide film.
2. The method of claim 1 , wherein depositing the first thickness of the silicon carbide material includes: (a) flowing one or more silicon-containing precursors into the reaction chamber; and (b) flowing one or more hydrogen radicals generated from a remote plasma source to react with the one or more silicon-containing precursors for a first time period, wherein depositing the second thickness of the silicon carbide material includes repeating operations (a) and (b) for a second time period.
To deposit each silicon carbide layer in the film densification method, silicon-containing precursors are flowed into the reaction chamber, where a substrate is located. Hydrogen radicals generated from a remote plasma source are then introduced to react with the silicon-containing precursors for a specified time. This process is repeated for each layer. So, depositing the first layer, followed by the hydrogen plasma treatment of the first layer, is followed by depositing the second layer and then hydrogen plasma treatment of the second layer to increase density of the SiC film.
3. The method of claim 2 , wherein each of the one or more silicon-containing precursors have (i) one or more silicon-hydrogen bonds and/or silicon-silicon bonds, and (ii) one or more silicon-carbon bonds, silicon-nitrogen bonds, and/or silicon-oxygen bonds.
In the silicon carbide film densification method, the silicon-containing precursors used to deposit each layer possess specific chemical bonds. They have silicon-hydrogen or silicon-silicon bonds, and also silicon-carbon, silicon-nitrogen, or silicon-oxygen bonds. These specific bonds in the precursors react with the hydrogen radicals, leading to the silicon carbide film being deposited on the substrate, before the remote hydrogen plasma treatment, to increase the density of the SiC film.
4. The method of claim 3 , wherein each of the one or more silicon-containing precursors is selected from a group consisting of: a cyclic siloxane, a linear siloxane, an alkoxy silane, an alkyl silane, and a silazane.
For the silicon carbide film densification, the silicon-containing precursors used in the deposition step can be chosen from a variety of specific compounds. These include cyclic siloxanes, linear siloxanes, alkoxy silanes, alkyl silanes, and silazanes. These precursors are reacted with hydrogen radicals to deposit layers of silicon carbide, which are then treated with remote hydrogen plasma to increase the density of the SiC film.
5. The method of claim 2 , wherein at least 90% of the hydrogen radicals are hydrogen radicals in a ground state.
In the silicon carbide film densification method, the hydrogen plasma used for treatment consists primarily (at least 90%) of hydrogen radicals in their ground state. This means the hydrogen radicals are in their lowest energy state. These ground-state hydrogen radicals are used to treat each deposited layer of silicon carbide to promote cross-linking and densification during the process of creating a thin, dense film.
6. The method of claim 2 , wherein the first time period is different than the second time period.
In the silicon carbide film densification method, the time period for reacting the silicon-containing precursors with hydrogen radicals to deposit the first silicon carbide layer can be different from the time period used to deposit the second silicon carbide layer. Both layers are then treated with remote hydrogen plasma to increase density of the SiC film, and the different deposition times allow for fine-tuning of the film's properties.
7. The method of claim 2 , wherein the first time period is identical to the second time period.
In the silicon carbide film densification method, the time period for reacting the silicon-containing precursors with hydrogen radicals is identical for both the first and second silicon carbide layers. Then both layers are treated with remote hydrogen plasma. Maintaining the same deposition time for each layer ensures uniformity and simplifies the process.
8. The method of claim 1 , wherein exposing the first thickness of the silicon carbide material to remote hydrogen plasma treatment includes: (c) flowing a source gas of hydrogen into a remote plasma source; (d) flowing an inert gas with the source gas of hydrogen; (e) generating, from the source gas of hydrogen, radicals of hydrogen in the remote plasma source; and (f) flowing the radicals of hydrogen to the first thickness of the silicon carbide material, wherein exposing the second thickness of the silicon carbide material to remote hydrogen plasma treatment includes repeating operations (c) through (f) on the second thickness of the silicon carbide material.
The remote hydrogen plasma treatment used to densify each silicon carbide layer includes several steps. First, hydrogen gas is flowed into a remote plasma source. An inert gas might be added. The plasma source generates hydrogen radicals from the hydrogen gas. These hydrogen radicals are then directed towards the deposited silicon carbide layer on the substrate to densify the layer before the next layer of SiC is deposited. This process is repeated for each silicon carbide layer.
9. The method of claim 8 , wherein the inert gas is helium, the source gas of hydrogen in the helium having a concentration of 1-10% hydrogen.
The inert gas used with the hydrogen gas in the remote plasma source for silicon carbide film densification is helium. The hydrogen gas is present in a low concentration, specifically between 1% and 10% of the helium mixture, which then helps make hydrogen radicals. These radicals are directed toward the deposited layers to densify them as the SiC film is being made.
10. The method of claim 8 , wherein at least 90% of the hydrogen radicals are hydrogen radicals in a ground state.
During the silicon carbide film densification, at least 90% of the hydrogen radicals generated in the remote plasma source are in their ground state. These ground-state hydrogen radicals are directed towards the silicon carbide layers to densify them after each deposition step, where hydrogen gas is flowed into the remote plasma source. An inert gas might be added. The plasma source generates hydrogen radicals from the hydrogen gas.
11. The method of claim 8 , wherein exposing the first thickness of the silicon carbide material to remote hydrogen plasma treatment further includes: (g) flowing a co-reactant gas with the source gas, wherein the co-reactant gas includes oxygen (O 2 ), nitrogen (N 2 ), carbon dioxide (CO 2 ), carbon monoxide (CO), water (H 2 O), methanol (CH 3 OH), ozone (O 3 ), nitrous oxide (N 2 O), ammonia (NH 3 ), diazene (N 2 H 2 ), methane (CH 4 ), ethane (C 2 H 6 ), acetylene (C 2 H 2 ), ethylene (C 2 H 4 ), diborane (B 2 H 6 ), or combinations thereof, wherein exposing the second thickness of the silicon carbide material to remote hydrogen plasma treatment further includes repeating operation (g) to the second thickness of the silicon carbide material.
The remote hydrogen plasma treatment, used to densify the silicon carbide layers includes flowing a co-reactant gas along with the source gas. Example co-reactant gases: oxygen, nitrogen, carbon dioxide, carbon monoxide, water, methanol, ozone, nitrous oxide, ammonia, diazene, methane, ethane, acetylene, ethylene, diborane, or combinations thereof. These co-reactant gases may alter the composition/properties of the silicon carbide film after being deposited and treated with remote hydrogen plasma for densification.
12. The method of claim 11 , wherein the co-reactant gas includes O 2 or N 2 .
In the silicon carbide film densification method, the co-reactant gas mixed with the source gas and flowed into the remote plasma source is either oxygen (O2) or nitrogen (N2). These gases react with the silicon carbide layer during the plasma treatment to modify the film's properties during the process to densify the film.
13. The method of claim 1 , wherein a pressure in the reaction chamber is between about 0.2 Torr and about 5 Torr.
During the silicon carbide film densification method, the pressure inside the reaction chamber is maintained between 0.2 Torr and 5 Torr. This pressure range optimizes the deposition and plasma treatment processes to promote film density. The first layer of SiC is deposited and treated with remote hydrogen plasma. Then the second layer of SiC is deposited and treated with remote hydrogen plasma.
14. The method of claim 1 , wherein depositing the first thickness of the silicon carbide material, exposing the first thickness of the silicon carbide material to remote hydrogen plasma treatment, depositing the second thickness of the silicon carbide material, and exposing the second thickness of the silicon carbide material to remote hydrogen plasma treatment occur without introducing a vacuum break.
The silicon carbide film densification method is performed without breaking vacuum between the deposition and plasma treatment steps. This means that after depositing a layer of silicon carbide, the remote hydrogen plasma treatment is performed immediately, without venting the reaction chamber. This seamless transition helps prevent contamination and ensures optimal film quality, where the 1st layer and 2nd layer of SiC are deposited and then treated with remote hydrogen plasma.
15. The method of claim 1 , wherein the substrate has a plurality of features, each of the features having a depth to width aspect ratio of greater than 5:1.
The substrate used in the silicon carbide film densification method has features with a high aspect ratio, meaning the depth of each feature is more than five times its width (greater than 5:1). This method is particularly useful for coating substrates with complex geometries, where the layers of SiC film are deposited and treated with remote hydrogen plasma for densification.
16. The method of claim 1 , wherein the silicon carbide film, prior to exposing the first and second thickness of the silicon carbide material to remote hydrogen plasma treatment, includes (1) Si—O and/or Si—C bonds, and (2) terminal CH 3 bonds, Si—OH bonds, and/or Si—H bonds.
Before the remote hydrogen plasma treatment, the deposited silicon carbide film on the substrate contains specific chemical bonds. It includes silicon-oxygen (Si-O) and/or silicon-carbon (Si-C) bonds, as well as terminal methyl (CH3), silicon-hydroxyl (Si-OH), and/or silicon-hydrogen (Si-H) bonds. These bonds are present in the film prior to densification and treatment with remote hydrogen plasma.
17. The method of claim 16 , wherein the remote hydrogen plasma treatment is configured to increase a number of Si—O and/or Si—C bonds, and decrease a number of the terminal CH 3 bonds, Si—OH bonds, and/or Si—H bonds in the silicon carbide film.
The remote hydrogen plasma treatment is designed to alter the chemical bonds in the silicon carbide film. It increases the number of silicon-oxygen (Si-O) and/or silicon-carbon (Si-C) bonds, while decreasing the number of terminal methyl (CH3), silicon-hydroxyl (Si-OH), and/or silicon-hydrogen (Si-H) bonds. This shift in bond composition leads to a denser and more stable silicon carbide film after the SiC layers are deposited.
18. The method of claim 1 , wherein the silicon carbide film is a doped silicon carbide film, the doped silicon carbide film including silicon oxycarbide (SiCO), silicon nitricarbide (SiCN), or silicon oxynitricarbide (SiONC) on the substrate.
The silicon carbide film being densified can be a doped silicon carbide film. This doped film contains silicon oxycarbide (SiCO), silicon nitricarbide (SiCN), or silicon oxynitricarbide (SiONC) on the substrate. The deposition of the doped silicon carbide is followed by remote hydrogen plasma treatment to densify the film.
19. The method of claim 1 , wherein exposing the first thickness of the silicon carbide material to remote hydrogen plasma treatment occurs for a duration between about 5 seconds and about 50 seconds, and exposing the second thickness of the silicon carbide material to remote hydrogen plasma treatment occurs for a duration between about 5 seconds and about 50 seconds.
The duration of the remote hydrogen plasma treatment for each silicon carbide layer is between 5 seconds and 50 seconds. The first layer of SiC is deposited, and treated with plasma for 5-50 seconds. The second layer of SiC is deposited, and treated with plasma for 5-50 seconds. This relatively short treatment time is sufficient to achieve the desired level of film densification without damaging the substrate or altering the film's composition excessively.
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December 16, 2016
December 5, 2017
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